Foams and processes for their production are well known in the art. Such foams are typically produced by reacting ingredients such as a polyisocyanate with an isocyanate reactive material such as a polyol in the presence of a blowing agent.
Synthetic foams have many uses and are produced in many forms. Rigid foam insulation panels are used in the construction of buildings. Foam bun stock is used for freezer insulation. Flexible foam is used in the manufacture of automobiles and furniture. Shaped foam products are used for building facades and ornamental effects for both interior and exterior uses.
Foam products are generally highly flammable when made solely out of their basic components. A variety of materials have been used in the past for imparting fire resistance to foams. For example, standard liquid flame retardants such as TRIS (-chloro-2-propyl) phosphate products, commercially available as ANTI-BLAZE 80 from Albright and Wilson and as PCF from Akzo Nobel have been conventionally used to increase the fire resistance of the foam. Such additives can be used to produce Factory Mutual Class 1 rated foam when organic halogenated hydrocarbons, such as 1,1-dichloro-1-fluorethane (HCFC-141b) are used as the primary blowing agent. However, similar foams made with non-halogenated hydrocarbons, such as iso-pentane and/or cyclopentane, used as the primary blowing agent fail to produce Factory Mutual Class 1 rated foam.
The use of expandable graphite as a fire retardant for polymer foams is generally known through the teaching of U.S. Pat. No. 3,574,644. It has been shown that particle size has an impact on the effectiveness of expandable graphite as a fire retardant. For example, U.S. Pat. No. 5,169,876 teaches the effective use of expandable graphite in a flexible polyurethane foam with a particle size of 300 to 1000 microns, but that use of expandable graphite having a particle size of less than 200 microns is ineffective.
It is desirable to produce foam and foam products having improved fire resistance and/or self extinguishing characteristics. Since the use of certain halogenated hydrocarbons may have detrimental environmental effects, it is also desirable to provide foam made with a non-halogenated hydrocarbon as the primary blowing agent.